Rotation of charged polymer particles for potential applications in micro-propulsion systems†
The possibility of an interelectrode oscillation behavior of dielectric dispersoids in colloidal dispersion by electric stimuli has been suggested but has not yet been reported. Here, we present a strategy for inducing the oscillation behavior based on dielectric constant (ε)-matching and conductivity (σ)-mismatching techniques between the dispersoids and dispersion medium. One of the electrophoresis-based bio-microparticles, Nannochloropsis gaditana (N. gaditana, ε ≈ 2.9–3.7), and olive oil, which has a similar dielectric constant (ε ≈ 3.1), were selected as dispersoid and dispersion medium, respectively. The conductivity mismatch was formed by controlling the temperature of the suspension. As the temperature increased from 25 to 50, 75, and 100 °C, the conductivity mismatch increased exponentially from 0.20 to 0.57, 2.17, and 11.95 (× 10−4 μS m−1). The anaphoretic separation behavior of the dispersoids by electric stimuli, which was shown at 25 °C, changed to interelectrode oscillation behavior at 100 °C due to their high conductivity mismatch, as we expected.